openSUSE Leap is a brand new way of building openSUSE and is new type of hybrid Linux distribution. Leap uses source from SUSE Linux Enterprise (SLE), which gives Leap a level of stability unmatched by other Linux distributions, and combines that with community developments to give users, developers and sysadmins the best stable Linux experience available. Contributor and enterprise efforts for Leap bridge a gap between matured packages and newer packages found in openSUSE’s other distribution Tumbleweed.
The first release of Leap was November 4, 2015, with the release of openSUSE Leap 42.1. The second release of openSUSE Leap, 42.2, was released November 16, 2016. Leap will have minor releases and users are expected to upgrade to the latest minor release within 6 months of its availability, leading to a life cycle of 18 months of maintenance and security updates per minor release. The 42 series of Leap is expected to achieve an estimated 36 months of maintenance and security updates.
Why change?

It secures the future of openSUSE while providing a more stable option for our users. Maintaining a distribution is a lot of work, especially when Stability is a goal. By basing openSUSE on SLE (SUSE Linux Enterprise), the core of Leap will be maintained by SUSE engineers. That means it will get fixes and security updates from SLE.
The openSUSE project can then replace and add the bits and pieces of software that contributors want and are willing to maintain.
openSUSE Leap will also complement Tumbleweed better. When there was one openSUSE, it was torn between those who wanted newer software and those who wanted a stable system. Tumbleweed caters to those who want newer software, which allows the regular release to do an even better job of providing a highly stable system.